Discourse representation theory

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Discourse representation theory (DRT) is a framework offering a representation language for the examination of contextually dependent meaning in discourse. DRT was created by Hans Kamp in 1981. A very similar theory was developed independently by Irene Heim in 1982, under the name of File Change Semantics (FCS).

In one sense, DRT offers a variation of first-order predicate calculus -- its forms are pairs of first-order formulae and the free variables that occur in them. In traditional natural language semantics, only individual sentences are examined, but the context of a dialogue plays a role in meaning as well. For example, anaphoric pronouns such as he and she rely upon previously introduced individual constants in order to have meaning. DRT uses variables for every individual constant in order to account for this problem. A discourse is represented in a discourse representation structure (DRS), a box with variables at the top and the sentences in the formal language below in the order of the original discourse. Sub-DRS can be used for different types of sentences.

One of the major advantages of DRT is its ability to properly represent donkey sentences:

  • Every farmer who owns a donkey beats it.
  • Every police officer who arrested a murderer insulted him.

These sentences present a problem when represented in first-order logic. The solution that DRT provides for the donkey sentence problem can be roughly outlined as follows: The common semantic function of non-anaphoric Noun Phrases is the introduction of a new Discourse Referent (DR), which is in turn available for the binding of anaphoric expressions.

Beyond this basic function, non-anaphoric noun phrases subdivide into genuine quantifiers (e.g., 'every professor'), and non-quantificational NPs (e.g., the indefinite NP 'a book'). Only the former bear scope. An 'every-NP' triggers the introduction of a complex condition of the form K 1 → K2, where K 1 and K 2 are sub-DRSs representing the restriction and the scope of the quantification respectively. Indefinite NPs just contribute a new DR (together with some descriptive material in terms of conditions on the DR), which is placed in a larger structure. This larger structure can be the top-level DRS or some sub-DRS according to the sentence-internal environment of the analyzed NP.

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[edit] References

  • Kadmon, N. 2001. Formal Pragmatics: Semantics, Pragmatics, Presupposition, and Focus. Oxford: Blackwell Publishers.
  • Kamp, Hans and Reyle, U. 1993. From Discourse to Logic. Kluwer, Dordrecht.